1 /*
2 * Copyright (c) 2003 Russell King <rmk@arm.linux.org.uk>
3 * Copyright (c) 2011-2013 Denys Vlasenko <vda.linux@googlemail.com>
4 * Copyright (c) 2011-2015 Dmitry V. Levin <ldv@altlinux.org>
5 * Copyright (c) 2015-2018 The strace developers.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 /* Return codes: 1 - ok, 0 - ignore, other - error. */
32 static int
arch_get_scno(struct tcb * tcp)33 arch_get_scno(struct tcb *tcp)
34 {
35 kernel_ulong_t scno = 0;
36
37 /* Note: we support only 32-bit CPUs, not 26-bit */
38
39 #if !defined(__ARM_EABI__) || ENABLE_ARM_OABI
40 if (arm_regs.ARM_cpsr & 0x20) {
41 /* Thumb mode */
42 goto scno_in_r7;
43 }
44 /* ARM mode */
45 /* Check EABI/OABI by examining SVC insn's low 24 bits */
46 errno = 0;
47 scno = ptrace(PTRACE_PEEKTEXT, tcp->pid, (void *)(arm_regs.ARM_pc - 4), NULL);
48 if (errno)
49 return -1;
50 /* EABI syscall convention? */
51 if (scno != 0xef000000) {
52 /* No, it's OABI */
53 if ((scno & 0x0ff00000) != 0x0f900000) {
54 error_msg("pid %d unknown syscall trap 0x%08lx",
55 tcp->pid, scno);
56 return -1;
57 }
58 /* Fixup the syscall number */
59 scno &= 0x000fffff;
60 } else {
61 scno_in_r7:
62 scno = arm_regs.ARM_r7;
63 }
64 #else /* __ARM_EABI__ || !ENABLE_ARM_OABI */
65
66 scno = arm_regs.ARM_r7;
67
68 #endif
69
70 /*
71 * Do some sanity checks to figure out
72 * whether it's really a syscall entry.
73 */
74 if (arm_regs.ARM_ip && !scno_in_range(scno)) {
75 debug_msg("pid %d stray syscall exit: ARM_ip = %ld, scno = %ld",
76 tcp->pid, arm_regs.ARM_ip, scno);
77 return 0;
78 }
79
80 tcp->scno = scno;
81 return 1;
82 }
83